This invention relates to a synthetic resin (i.e., plastic) dressing, and to a method or process of treatment wherein the dressing may optionally contain various time release medicinal or drug agents. More specifically, in veterinary use, the dressing of the present invention may be applied to a site as a paste and allowed to set-up in place on the site or, alternatively, the dressing of this invention may be pre-cured and pre-formed and then applied to the treatment site. The preformed material may be attached to an elastic fabric to further improve its use by preventing adherence to the overlying dressing and also preventing cracking of the dressing. Still further, the dressing and treatment method of the present invention may be used in the transdermal or topical administration of a variety of drugs.
More generally, in the standard current treatment of wounds, is however, such as severe burn wounds, a topical medicinal agent, such as an antimicrobial agent (e.g., silver sulfadiazine or the like), is applied to a layer of gauze, and prior to the application of the gauze on the wound site, the medicated gauze is cut to the size and shape of the open wound area so as to prevent maceration of adjacent unburned or healed skin. Care is taken to protect the burn wound areas from coming into contact with one another as, for example, by placing folded gauze between burned apendages, and between the the ear and head, after the initial medicated gauze has been applied to the burn wound sites. Then, fluffed gauze or other bulky dressings may be applied, if it is desired to maintain warm body temperatures. A Kling wrap or the like may be used to secure the dressings in place. The patient's extremities and joints are arranged in a desired position. Typically, the dressings are changed one or more times each day, allowing the physician to observe the healing of the wound and to reapply the medicinal agent. The repeated changing of the dressing causes intense pain to the patient, risks contamination of the wound with microbial infection, disturbs the healing process, and requires considerable time of the treating physician or clinician, thus substantially increasing the cost of treatment. Such daily changing of dressings is typically required until the wound has healed, or until the wound is grafted. Often times, such periodic changing of the dressing is required for a period up to two or three weeks.
Heretofore, various burn wound treatments have been utilized in which a synthetic resin film or coating dressing is applied to the wound site as a paste so as to cure or set up in place thereby to serve as a skin covering for the burn wound lesion during the healing process. While such in-situ settable synthetic resin dressings have gained wide clinical usage in burn treatment, the set-up or hardening time required by many such previous synthetic resin dressings was unduly long. Such extended set-up times required the continued attendance of the treating physician, and is often painful to the patient due to the uncomfortable position the patient must maintain during the entire dressing or paste set-up period.
One such in situ plastic wound bandage is disclosed in U.S. Pat. No. 4,272,518 to Moro et al, which is a settable paste consisting of a polymer (e.g., a three-dimensional, 2-hydroxyethylmethacrylate), and an inert, normally liquid solvent (e.g., polyethylene glycol). While this plastic wound bandage paste worked well for its intended purpose in that a non-tacky, homogeneous, occlusive film was formed on the surface of the wound, relatively long and unpredictable set-up times (in some instances up to an hour) resulted when useful ratios of solvent vis-a-vis the polymer were mixed. Also, in many instances, the resulting film bandage formed on the wound site became brittle and was subject to cracking or splitting, especially upon movement of the patient, thus rendering the plastic film substantially ineffective as a barrier against personnel, patient or environmentally transmitted bacteria and the like.
Various pastes made from organic solvent soluble polymers of hydroxyalkylacrylates and methlacrylates (known as HEMA pastes) are described in U.S. Pat. No. 3,868,447 to Kliment for use as a sound energy transfer media in ultrasound diagnostic testing, as a carrier of local anesthestics in dental surgery, or as a protective layer over dental fillings during setting.
U.S. Pat. No. 3,575,946 to Chromechek et al discloses various solvent soluble polymers of ethylene glycol, a monomethacrylate and monoacrylate contaminated with various percentages of dimethacrylates or bisacrylates.
A water soluble polymer of hydroxyalkylacrylate or methacrylate is disclosed in U.S. Pat. No. 3,576,760 to Gould et al in which a variety of drugs, pesticides, flavoring agents and fragrances can be entrapped.
In U.S. Pat. No. 3,577,516 to Gould et al, a spray-on bandage is disclosed in which a hydrophilic water insoluble polymer, such as a hydroxy lower alkylacrylate or ethylacrylate, is disclosed as a high boiling point plasticizer or solvent, is sprayed onto the wound area site so as to form an in situ bandage.
Environmental wound barrier dressings or hydrophilic, water insoluble, organic soluble polymers of hydroxyalkyl methacrylate or acrylate are disclosed in U.S. Pat. No. 3,963,685 to Abrahms, and are commercially available under the trademark HYDRON from Abbott Laboratories of Chicago, Ill. While other such barrier dressings have met with commercial acceptance, these dressings may have a tendency to crack, thus necessitating repair of the cracks or fissures therein.
Reference may also be made to the following U.S. patents for examples of various tapes, bandages, or other dressings for carrying a supply of time-released, medicinal agents which are topically applied to the skin or wound site for transdermal absorption: U.S. Pat. Nos. 3,896,789, 3,955,566, 4,012,497, 4,073,291, 4,122,158, 4,136,162, 4,164,559, 4,191,743, 4,268,497, 4,292,299, 4,310,509, and 4,307,075.
Walliczek, U.S. Pat. No. 4,243,656, discloses a biosynthetic polymeric burn wound dressing containing a polyacrylate polymer, humectants, such as glycerol, gelatin, and water, which is supplied to the wound site.
In U.S. Pat. No. 3,551,554 to Herchler, a method of enhancing tissue penetration of a variety of topically applied physiologic active agents not contained in a solid delivery system is disclosed by topically applying the agent to the skin, together with a relatively high concentration (e.g., 50-90%) of dimethylsulfoxide (DMSO).
Keith et al, U.S. Pat. No. 4,294,820, discloses a polymeric diffusion matrix for the sustained transdermal delivery of a medicinal (e.g., phenylephrine). Like the prior patent to Herchler, Keith et al disclose the use of high concentrations of DMSO as a skin absorption facilitator or skin penetration enhancer.